GTK: Cache our GdkCursor objects, since building them hits the disk.

chrome/common/gtk_util.cc

Index: chrome/common/gtk_util.cc
diff --git a/chrome/common/gtk_util.cc b/chrome/common/gtk_util.cc
index e0268773d8770100255606b732437512c6c46ff1..663190c732b736abcece36f264c912a57f0bbf4a 100644
--- a/chrome/common/gtk_util.cc
+++ b/chrome/common/gtk_util.cc
@@ -58,6 +58,38 @@ GList* GetIconList() {
   return icon_list;
 }
 
+// A process wide singleton that manages our usage of gdk
+// cursors. gdk_cursor_new() hits the disk in several places and GdkCursor
+// instances can be reused throughout the process.
+class GdkCursorCache {
+ public:
+  ~GdkCursorCache() {
+    for (std::map<GdkCursorType, GdkCursor*>::iterator it =
+             cursor_cache_.begin(); it != cursor_cache_.end(); ++it) {
+      gdk_cursor_unref(it->second);
+    }
+    cursor_cache_.clear();
+  }
+
+  GdkCursor* GetCursorImpl(GdkCursorType type) {
+    std::map<GdkCursorType, GdkCursor*>::iterator it = cursor_cache_.find(type);
+    GdkCursor* cursor = NULL;
+    if (it == cursor_cache_.end()) {
+      cursor = gdk_cursor_new(type);
+      cursor_cache_.insert(std::make_pair(type, cursor));
+    } else {
+      cursor = it->second;
+    }
+
+    // Add a reference to the returned cursor because our consumers mix us with
+    // gdk_cursor_new() calls which return a +1 refcount.
+    gdk_cursor_ref(cursor);

[Evan Martin, 2009/09/12 00:37:05]

Won't this cause a +2 refcount on a cache miss?

+    return cursor;
+  }
+
+  std::map<GdkCursorType, GdkCursor*> cursor_cache_;
+};
+
 }  // namespace
 
 namespace event_utils {
@@ -474,4 +506,9 @@ GdkColor AverageColors(GdkColor color_one, GdkColor color_two) {
   return average_color;
 }
 
+GdkCursor* GetCursor(GdkCursorType type) {
+  static GdkCursorCache impl;
+  return impl.GetCursorImpl(type);
+}
+
 }  // namespace gtk_util